The U.S. space agency NASA says storm damage repairs are likely to keep the space shuttle Atlantis grounded at least until May, two months after it was originally set to visit the International Space Station. But as we hear from VOA's David McAlary, NASA officials say the delay will not postpone completion of the research outpost in three years.

NASA says the storm that pounded the Florida launch site three weeks ago with hail the size of golf balls left about 2,500 dents in the layer of insulating foam that covers the shuttle's huge external fuel tank.

Atlantis was rolled back to its hangar, where engineers this week began patiently sanding the smallest pits. Bigger divots will require new foam to be poured or sprayed.

Shuttle program manager Wayne Hale says he should know by April 10 whether the dented fuel tank can be repaired or whether a new one will have to be attached to Atlantis.

Hale says it is possible to launch Atlantis to the space station in May if the current tank can be fixed. "We need to see how quickly we can make repairs and what the final number and types of repairs come out of the engineering assessments. So I am hesitant to tell you what the earliest launch date would be based on repairing this tank. It is possible that we could still squeak into the May part of the launch window. If we do go to the other tank, we are probably looking at the middle of June," he said.

Atlantis will be the first shuttle this year to continue space station construction. Its cargo is a new set of solar arrays for the starboard side of the outpost.

NASA's Associate Administrator for Space Operations, Bill Gerstenmaier says Atlantis' launch date is of less concern than the proper repair of the foam. "Our ultimate goal is to get a good tank ready. We did not want to pick a date and then have the work get forced to fit that date, whatever it was. We think it is better at this point to just let the teams continue to work to get the tank in a ready-to-go-fly configuration. Out of their work will naturally follow what the right launch date is and what tank we ought to use," he said.

The integrity of the foam has been a NASA priority since a piece broke away during the launch of the orbiter Columbia in 2003 and punctured a wing. Seven astronauts died during re-entry when atmospheric gases superheated by friction with the shuttle entered the wing and destroyed it.

The insulation is essential to the shuttle's safety. Its prevents the frigid liquid oxygen and hydrogen fuel inside from condensing moisture in the humid Florida air and causing it to freeze on the tank. Ice, like the foam itself, is a potential hazard to the shuttle if it breaks away during launch.

Shuttle manager Hale says the delay of the Atlantis lift-off will not set back the goal of completing the international space station by 2010. He says that despite the postponement, shuttle launches will be back on schedule in about one year.